Anxiety neurosis means neurosis in a broad sense with anxiety being the predominant symptom. According to DSM-III edited by U.S. Society of Psychiatry in 1980, anxiety neurosis is classified into panic disorder and global anxiety neurosis.
It has been a practice to treat anxiety neurosis including panic disorder with the use of tricyclic antidepressive drugs or benzodiazepine anxiolytic drugs. However, it is pointed out that these drugs suffer from some problems. Namely, the tricyclic antidepressive drugs exert their effects slowly and give rise to cholinolytic side effects. On the other hand, the benzodiazepine anxiolytic drugs induce side effects of hypersedation, break-off phenomenon, etc. and, moreover, produce addiction. That is to say, there has been known no satisfactory remedy for anxiety neurosis.
On the other hand, N-(2-hydroxyethyl)nicotinamide nitrate (generic name: nicorandil) is a known compound which has been marketed as a remedy for angina pectoris and described in, for example, Japanese Patent Publication (Kokai) No. 52-122373. It is known that nicorandil has several effects in addition to the antianginal effect. For example, Japanese Patent Publication (Kokai) No. 53-9323 states that it is efficacious as a remedy for circulatory diseases, while Japanese Patent Publication (Kokai) No. 58-85819 points out its bronchodilating effect. Furthermore, Japanese Patent Publication (Kokai) No. 63-152317 discloses that nicorandil is useful as a remedy for diseases accompanied by cerebral ischemic lesion and Japanese Patent Publication (Kokai) No. 3-101621 indicates that it is useful as a hydroxyl radical scavenger. However, it has not been known that nicorandil and its analogs are useful in the treatment of anxiety neurosis, in particular, panic disorder.
As described above, the tricyclic antidepressive drugs conventionally employed in the treatment of anxiety neurosis, in particular, panic disorder exert their effects slowly and suffer from problems of giving rise to cholinolytic side effects (thirst, constipation, urinary difficulty, etc.) and other serious side effects. On the other hand, it is known that the benzodiazepine anxiolytic drugs induce side effects of hypersedation, break-off phenomenon, drug-addiction, muscle relaxation, etc. Thus, it has been urgently required to develop highly safe drugs by which panic disorder or the following anxiety can be prevented or ameliorated.